1. Field of the Invention
One aspect of the present invention relates to flexible polyurethane foam suitable for use in automobile interior applications, and method for making vegetable-based polyol to form foam.
2. Background Art
Flexible polyurethane foams have been extensively used in the automotive industry for applications such as seating, instrument panels, armrests, headrests and headliners. On average, 35 pounds of flexible polyurethane foam are used per vehicle for interior applications.
The production of polyurethane foams is well known in the art. Polyurethanes are formed when isocyanate (NCO) groups react with hydroxyl (OH) groups. One common method of polyurethane production includes the reaction of a polyol with OH groups and an isocyanate with NCO groups, which forms the backbone urethane group.
A blowing agent can be added to the reaction to cause gas or vapor to be evolved during the reaction. The blowing agent creates void cells in the final foam, and commonly is a solvent with a relatively low boiling point or is water. As the polyurethane reaction proceeds and the material solidifies, the vapor gas bubbled from the blowing agent are locked into place to form void cells. Varying the amount or type of blowing agent used may control the final polyurethane foam density and properties.
Other conventional components such as cross-linking agents and catalysts are often used in standard foam formulations. A cross-linking agent promotes chemical cross-linking to result in a structured final urethane product. A catalyst controls reaction kinetics to help tailor the final product qualities.
Polyols commonly used in the reaction are typically derived from petrochemicals, for example, glycerin and ethylene oxide. The use of petrochemical polyols is disadvantageous for a variety of reasons. First, since polyols are derived from petroleum, they are a non-renewable resource. Furthermore, the production of a polyol may require a great deal of energy and expense, as oil must be drilled, extracted from the ground, transported to refineries, refined, and otherwise processed to yield the polyol.
With uncertainties in the long-term economic stability and limited reserves of fossil fuels and oils, investigations into using renewable resources as a source for foams have been ongoing. As part of that investigation, soy-based polyols have been developed as an alternative to petroleum-based polyols. The soy-based polyols are considered a good alternative to petroleum-based polyols for the production of polyurethane foam since the soy-based polyols can offer cost advantages as well as alleviate the environmental concerns associated with petroleum-based polyols. Examples of the use of soy-based polyols to formulate soy-based polyurethane foams can be found in U.S. Patent Application Nos. 2002/009230, 2002/0192456, 2003/0083394 and U.S. Pat. Nos. 5,710,190 and 6,624,244.
In the manufacture of soy-based polyols, any combination of the following steps is commonly utilized: blowing air through a soy oil, heating the soy oil to an elevated temperature over room temperature and/or adding a catalyst to promote reaction in the soy oil.
While soy-based polyurethane foams have made inroads into various polyurethane foam markets, the use of soy-based polyurethane foam has not gained acceptance in the automotive industry because of certain limitations. One primary limitation of using soy-based polyurethane foams is the unpleasant vegetable oil odor that is prominent in these foams. This limitation is especially acute in the vehicle interior, where controlled air quality and odor are important issues for automobile consumers. In addition, the heated environment of the cabin interior provides additional limitations on the types of materials that can be used.
Commercially-available soy polyols contain low molecular weight species, for example, aldehydes and hydroperoxides, that contribute to the unpleasant odor emanating from the resulting soy-based polyurethane foams. These low molecular weight species can be formed when the soy oil is heated to elevated temperatures. Soy polyol suppliers have attempted to address this problem by masking the unpleasant odor with other chemicals, for example, fragrances. However, these techniques have not satisfactorily addressed the odor problem issue. Alternatively, a few soy polyols suppliers offer expodized soy polyols, which result in a reduction in unpleasant odor compared to other soy polyols. However, these expodized soy polyols come at a premium price compared to non-expodized soy polyols.
Accordingly, it is desirable and there is a need to provide soy-based polyurethane foam having an acceptable level of odor, and method to produce the same. Moreover, it is also desirable to provide an odor barrier for encapsulating the odor emanating from a soy-based polyurethane foam within a confined volume, and method to produce the same.